1. Technical Field
The technology disclosed herein relates to an imaging device. More specifically, the technology disclosed herein relates to an imaging device having a function for capturing 3D images (i.e., stereo images).
2. Background Information
As 3D has become increasingly popular in television and films in recent years, the trend is toward providing an environment in which the average user can easily view 3D images. In conjunction with this, there have been proposals for cameras and other such imaging devices capable of 3D imaging.
For example, in Japanese Laid-Open Patent Application 2001-109089 (hereinafter referred to as “Patent Literature 1”) is proposed a stereo imaging device composed of a two-system camera, with which an image with a good 3D feel can be captured even though a small lens is used. In Japanese Laid-Open Patent Application H5-7374 (hereinafter referred to as “Patent Literature 2”) is proposed a stereo imaging device having a prism for obtaining left and right images with parallax, and this camera has a configuration that yields left and right parallax images with a single system, so the stereo imaging device can be obtained with a simple configuration.
Unlike 2D images, 3D images need to go through a process in which a person perceives an image as a stereo image in his brain from images with parallax. Accordingly, there is the risk that the result will cause an observer discomfort if the image has not be suitably adjusted by matching the images seen with the eyes to the process by which a person perceives a stereo image. Therefore, as in Japanese Laid-Open Patent Application 2008-187385 (hereinafter referred to as “Patent Literature 3”), there has been proposed a device with which, when a 3D image is captured with an imaging device that is compatible with 3D, changes the camera control method (in the case of Patent Literature 3, the period of exposure control, etc.) is changed by comparing to when a 2D image is captured.
Thus, with an imaging device capable of capturing 3D images, various considerations are taken into account besides just acquiring an image, such as how attractive the captured image looks, and safety. On the other hand, just as when capturing a 2D image, one of the things to which attention must be paid during the capture of a 3D image is blurring of the image caused by hand shake that occurs when the imaging device is held in the hands. This generally causes a phenomenon that is called visually induced motion sickness, so a risk with a 3D image is that blurring of the image will cause the observer more discomfort than with a 2D image.
As a technique for correcting image blurring caused by hand shake in hand-held imaging, there is a method in which movement of the imaging device is detected with an acceleration sensor, and the drive of a variable angle prism provided to the imaging optical system is controlled according to the result of this movement detection (see, for example, Japanese Laid-Open Patent Application S62-153816 hereinafter referred to as “Patent Literature 4”).
With the imaging device in Patent Literature 4, a variable angle prism, in which the interior of two sheets of glass connected with a special corrugated film is filled with a liquid having a high refractive index, is provided ahead of a solid state imaging element. The two sheets of glass of this variable angle prism are inclined in the horizontal and vertical directions, respectively, on the basis of information about the movement of the imaging device obtained from the acceleration sensor, and the optical axis of incident light is thereby bent, and movement of the captured image is stabilized.
In another example, there has been a proposal for an imaging optical system having a focus adjusting group or a zoom optical group, and a correcting optical mechanism in which the optical axis of this imaging optical system is inclined or made eccentric, as in Japanese Laid-Open Patent Application H5-66450 (hereinafter referred to as “Patent Literature 5”), for instance. With the imaging device in Patent Literature 5, a lens that is part of the imaging optical system composed of four lens groups shown in FIG. 2 of Patent Literature 5 is incorporated into a mechanism that is able to move up, down, left, and right via the slide shafts shown in FIG. 4 of Patent Literature 5, for example. This lens is moved by an electromagnetic actuator comprising a magnet and a coil, and this causes the optical axis of the imaging optical system to be eccentric or inclined. With this configuration, blurring of the image caused by shaking of the imaging device can be corrected by moving the slidable portion with the slide shafts (45y and 45p in FIG. 4 of Patent Literature 5) by means of the electromagnetic actuator according hand shaking during imaging.
Also, Japanese Laid-Open Patent Application H7-128619 (hereinafter referred to as “Patent Literature 6”) discloses a zoom optical system comprising an anti-shake mechanism designed so that blurring of the image is corrected when the zoom optical system vibrates, which is accomplished by moving a relatively small and lightweight lens group that constitutes part of the zoom optical system in a direction perpendicular to the optical axis.
Also, Japanese Laid-Open Patent Application H9-261524 (hereinafter referred to as “Patent Literature 7”) discloses a method in which image movement is corrected by moving an imaging element (specifically, CCD) in a direction perpendicular to the optical axis.
Further, Japanese Laid-Open Patent Application H4-331586 (hereinafter referred to as “Patent Literature 8”), for example, discloses a video camera having means for detecting the inclination of the camera body, decision means for deciding the extent of the inclination from a signal obtained by the detection means, means for rotating an imaging element, and means for controlling the rotation means. Japanese Laid-Open Patent Application 2006-171528 (hereinafter referred to as Patent Literature 9) discloses a camera capable of moving the imaging element in three directions: the roll direction whose center axis is the optical axis, and the left-right and up-down directions perpendicular to the optical axis.
In Patent Literature 4 to 7 and Patent Literature 9, an angular velocity sensor (so-called gyro sensor) which detects shaking of the imaging device is used for blurring detection. More specifically, the shake angle of the imaging device is found by performing integration on the angular velocity of movement of the imaging device detected by the angular velocity sensor, and drive of the above-mentioned variable angle prism or the like is controlled according to this shake angle. Also, in the example of Patent Literature 8, the means for detecting the inclination of the camera was one that made use of gravitational force or acceleration, and inclination of the captured image (shake in the roll direction) was cancelled out by rotationally driving the imaging element according to the inclination of the camera body.